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PlasmaDensity
ne(m3)		Electron temperature
T(K)		Magnetic field
B(T)		Debye length
λD(m)
Gas discharge1016104--10−4
Tokamak10201081010−4
Ionosphere101210310−510−3
Magnetosphere10710710−8102
Solar core1032107--10−11
Solar wind10610510−910
Interstellar medium10510410−1010
Intergalactic medium1106--105

Source: Chapter 19: ''The Particle Kinetics of Plasma''

http://www.pma.caltech.edu/Courses/ph136/yr2002/


Hannes Alfven pointed out that: "In a low density plasma, localized space charge regions may build up large potential
drops over distances of the order of some tens of the Debye lengths. Such regions have
been called electric double layers. An electric Double Layer is the simplest space charge
distribution that gives a potential drop in the layer and a vanishing electric field on each
side of the layer. In the laboratory, double layers have been studied for
half a century, but their importance in cosmic plasmas has not been generally recognized.".


DEBYE LENGTH IN A PLASMA

In a plasma, the Debye length is

: \lambda_D = \sqrt{ rac{ arepsilon_0 k/q_e^2}{n_e/T_e+\sum_{ij} j^2n_{ij}/T_i}}

where

: λ''D'' is the Debye length,
: ε0 is the Permittivity Of Free Space ,
: ''k'' is Boltzmann's Constant ,
: ''q''''e'' is the charge on an electron,
: ''Te'' and ''Ti'' are the temperatures of the electrons and ions, respectively,
: ''ne'' is the density of electrons,
: ''nij'''is the density of atomic specie ''i'', with positive Ion ic charge ''jq''''e''

The ion term is often dropped, giving

: \lambda_D = \sqrt{ rac{ arepsilon_0 k T_e}{n_e q_e^2}}

although this is only valid when the ions are much colder than the electrons.


DEBYE LENGTH IN AN ELECTROLYTE

In an electrolyte, the Debye length is

: \lambda_D = \sqrt{ rac{ arepsilon_0 arepsilon_r k T}{2 N_A e^2 I}}

where
: ''I'' is the Ionic Strength of the electrolyte,
: ''NA'' is Avogadro's Number .

or when mono-monovalent and symmetrical,

: \lambda_D = \sqrt{ rac{ arepsilon_0 arepsilon_r R T}{2 F^2 C_0}}


REFERENCES